Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for 3C 273: 04-22 (93), 04-23 (93), 04-24 (93), 04-25 (93), 04-26 (93) — by astronomy; check the weather when the night is within four days.

2038-04-11astronomy score per night — click a bar for that night2038-05-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-04-11 Sun	89	—	unknown	21:40–04:25 (good, 6.75 h)	50.1° 00:30	7.52	42%	83.5°
2038-04-12 Mon	84	—	unknown	21:40–04:20 (good, 6.67 h)	50.1° 00:25	7.46	52%	70.6°
2038-04-13 Tue	72	—	unknown	23:05–04:15 (good, 5.17 h)	50.1° 00:25	7.4	62%	57.3°
2038-04-14 Wed	52	—	unknown	21:45–04:40 (marginal, 6.92 h)	50.1° 00:20	7.35	73%	43.5°
2038-04-15 Thu	32	—	unknown	21:45–04:25 (marginal, 6.67 h)	50.1° 00:15	7.29	82%	29.2°
2038-04-16 Fri	23	—	unknown	21:45–04:10 (marginal, 6.42 h)	50.1° 00:10	7.23	90%	14.5°
2038-04-17 Sat	18	—	unknown	00:35–03:50 (marginal, 3.25 h)	50.1° 00:10	7.17	96%	0.5°
2038-04-18 Sun	19	—	unknown	21:50–01:10 (marginal, 3.33 h)	50.1° 00:05	7.11	99%	15.7°
2038-04-19 Mon	26	—	unknown	21:50–03:25 (marginal, 5.58 h)	50.1° 00:00	7.06	100%	31.0°
2038-04-20 Tue	47	—	unknown	21:50–03:45 (marginal, 5.92 h)	50.1° 23:55	7.0	96%	46.1°
2038-04-21 Wed	92	—	unknown	21:55–01:00 (good, 3.08 h)	50.1° 23:50	6.94	91%	61.0°
2038-04-22 Thu	93	—	unknown	21:55–02:50 (good, 4.92 h)	50.1° 23:50	6.88	83%	75.5°
2038-04-23 Fri	93	—	unknown	21:55–03:15 (good, 5.33 h)	50.1° 23:45	6.82	74%	89.5°
2038-04-24 Sat	93	—	unknown	22:00–03:20 (good, 5.33 h)	50.1° 23:40	6.77	64%	103.0°
2038-04-25 Sun	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:35	6.71	53%	116.1°
2038-04-26 Mon	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:30	6.65	43%	128.7°
2038-04-27 Tue	93	—	unknown	22:05–03:20 (good, 5.25 h)	50.1° 23:30	6.59	34%	141.1°
2038-04-28 Wed	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:25	6.53	25%	153.2°
2038-04-29 Thu	93	—	unknown	22:05–03:10 (good, 5.08 h)	50.1° 23:20	6.47	17%	165.2°
2038-04-30 Fri	93	—	unknown	22:10–03:10 (good, 5.0 h)	50.1° 23:15	6.42	11%	177.1°
2038-05-01 Sat	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.1° 23:15	6.36	6%	171.1°
2038-05-02 Sun	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:10	6.3	2%	159.3°
2038-05-03 Mon	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:05	6.24	0%	147.5°
2038-05-04 Tue	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:00	6.19	0%	135.5°
2038-05-05 Wed	93	—	unknown	22:15–02:50 (good, 4.58 h)	50.1° 22:55	6.13	2%	123.5°
2038-05-06 Thu	93	—	unknown	22:20–02:45 (good, 4.42 h)	50.1° 22:55	6.07	6%	111.4°
2038-05-07 Fri	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.1° 22:50	6.01	11%	99.1°
2038-05-08 Sat	90	—	unknown	22:20–02:35 (good, 4.25 h)	50.1° 22:45	5.96	18%	86.6°
2038-05-09 Sun	85	—	unknown	22:25–02:35 (good, 4.17 h)	50.1° 22:40	5.9	27%	73.9°
2038-05-10 Mon	73	—	unknown	22:25–02:30 (good, 4.08 h)	50.1° 22:35	5.85	37%	60.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-04-11&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.